This invention relates generally to a rapid leak detection apparatus and method for aboveground fluid storage tanks. More particularly, the present invention relates to an apparatus and method for the rapid detection and location of fluid leaks from aboveground fluid storage tanks.
Currently there are two principal systems and methods for leak testing of aboveground fluid storage tanks. Vacuum box testing requires the emptying of the tank, cleaning the tank floor and applying a vacuum to portions of the tank floor to test for leaks. Under this method, loss of vacuum from any portion of the tank floor is indicative of a leak in that portion of the tank floor. This testing method requires that the tank be taken out of service for a considerable period of time for cleaning and manual inspection, which with fuel storage tanks, typically poses substantial risk of injury to the tank inspectors. Moreover, the vacuum box system and method fails to detect very small defects in the tank. A second method utilizes sonic transducers placed at several points around the circumference of the tank. Under this method, fluid escaping from the tank will generate sonic waves which are sensed by the transducers. Triangulation from the transducer locations then localizes the leak. This sonic sensing method, however, suffers from ambient sonic interferences and, due to difficulty in verifying sensitivity, is of uncertain value for detecting very small leaks.
To date there are no known testing procedures for detection and localization of aboveground tank leaks without taking the tank out of service. The present invention provides a tracer leak detection method which utilizes a highly volatile liquid chemical added to the fluid stored in the tank. When a leak occurs in the tank structure, the fluid contained within tank leaks into the sand base underneath the tank. The tracer volatilizes and separates from the fluid by vaporization and disperses into the surrounding soil by molecular diffusion.